What you'll need to get started

What is calcium scale?

Calcium scale, sometimes also called limescale, “is a hard, off-white chalky substance often found on the metallic parts of water-operated machinery.”

Calcium build-up on your tile and plaster can be a result of hard water in your area.

Scaling starts out just looking a little like white foam around the water line.

That foamy looking white stuff becomes hard as a rock and if not treated regularly, almost impossible to remove.

Calcium scale can also start to clog your pool filter, coat your pipes, and overall just wreak some havoc on all your working parts!

But it also starts to erode materials underneath it, like your pool tiles, fiberglass, ladders, liner and grout.

Not only that, but it can cause some pretty nasty looking stains if left untreated, especially on vinyl.

Types of calcium scale

There are two main types of calcium scale you should know about:

1. Calcium carbonate

Carbonate scale is the most common type of scaling, and it is primarily affected by the pool’s pH levels.

High pH levels are what “drives calcium carbonate out of solution and into scale form.” [source]

2. Calcium silicate

Calcium silicate is a little more grayish-white than calcium carbonate.

It's also harder to get rid of and is usually caused by pH levels that are too high. [source]

How does calcium scale get in your pool?

Calcium scaling is usually caused by high calcium hardness levels, and triggered by high pH and high alkalinity. So it's important to test the calcium hardness levels in your pool every time you test the other chemicals. You can either do this yourself with a pool test kit, or bring a water sample into a pool service store to do it for you.

But usually if this level is off, the pH level will also be off, as pH is actually the agent that affects calcium buildup the most.

The reason for this is that a high pH level will cause the calcium that is naturally in the pool water to solidify and deposit itself on pool surfaces. This is what we call scaling and it can be a pain to get off!

Calcium scale deposits can also be left behind by evaporating water. You'll usually see this scaling right around the water line as well.

5 tips for preventing calcium scaling

Because calcium scaling is such a pain to remove, it is best to stay on top of preventing it by taking the following precautions:

1

Lower your pH (7.2-7.4) and alkalinity (80-90 ppm)

2

Use a pool clarifier to clump the calcium films together, then vacuum them away or let your filter take care of them

3

If you seem to be battling unusually high amounts, avoid shock with added calcium like calcium hypochlorite